Traditionally buildings have vertical elements (walls), horizontal elements (roofs), and cross bracing as may be necessary to overcome lateral forces such as wind loading and the like. Roof elements may be in the form of a beam (lintel), a triangle or a series of triangles (i.e. trusses), or a geodesic structure or conic section (i.e. an arch). The roof element can function alone when used as, so to speak "a pup tent" or "a nissen-hut" or as a bridge.
The required rigidity of buildings is assured by the weight of the components, by individual cross ties (bracing) and/or an infinite number of cross ties i.e. a plate or diaphram. These are found in various combinations and sub-combinations suited to the use or requirement of and for the building.